In many processes, including the production of glass, both plate glass and glass fibers, it is conventional to pelletize the particulate matter employing an aqueous pelletizing solution. The pellets are then dried and preheated prior to introduction into the furnace in which they are melted to form, in the glass art, molten glass from which the glass product, such as glass fibers, is produced.
The steps of drying and preheating the glass pellets are generally undertaken in two individual sections of a chamber. In the uppermost section, the pellets are dried under conditions which prevent their agglomeration. In the lower section, the substantially dry pellets are preheated to as high a temperature as feasible in consideration of the temperature of the gas stream with which they are contacted. Generally, the drying and preheating steps are carried out in superimposed beds in which there may, or may not, be a difference in regard to pellet movement, gas velocities, gas characteristics, and the like. However, due to the differences in what is sought to be accomplished in the drying step, either partial or complete, and the preheating step, it is often desirable to provide individual contact conditions in the two steps rather than to employ a conventional downward-moving bed in both steps. The method and apparatus of the present invention are directed to providing individual, different contact conditions in the drying and preheating steps of processing pellets of all kinds.